#! python3
# distance.py

import math

x1, y1, x2, y2 = [float(x) for x in input().split(' ')]
print('%.5f'%math.sqrt(pow(x2-x1, 2) + pow(y2-y1, 2)))
 import math math float(x) for x in input().split(' ') for x in input().split(' ') x input().split(' ') ().split () input split ' ' for x in input().split(' ') float(x) float x x1, y1, x2, y2 = [float(x) for x in input().split(' ')] x1 [float(x) for x in input().split(' ')] y1 x2 y2 print('%.5f'%math.sqrt(pow(x2-x1, 2) + pow(y2-y1, 2))) print '%.5f'%math.sqrt(pow(x2-x1, 2) + pow(y2-y1, 2)) '%.5f' math.sqrt(pow(x2-x1, 2) + pow(y2-y1, 2)) math.sqrt math sqrt pow(x2-x1, 2) + pow(y2-y1, 2) pow(x2-x1, 2) pow x2-x1 x2 x1 2 pow(y2-y1, 2) pow y2-y1 y2 y1 2 x1, y1, x2, y2 = [float(x) for x in input().split(' ')] [float(x) for x in input().split(' ')] x1 x2, y2 = [float(x) for x in input().split(' ')] [float(x) for x in input().split(' ')] x2 y1, x2, y2 = [float(x) for x in input().split(' ')] [float(x) for x in input().split(' ')] y1 y2 = [float(x) for x in input().split(' ')] [float(x) for x in input().split(' ')] y2
#! python3
# distance.py

import math

x1, y1, x2, y2 = [float(x) for x in input().split(' ')]
print('%.5f'%math.sqrt(pow(x2-x1, 2) + pow(y2-y1, 2)))

